Green Woodpecker: Aggressive behaviour

I recently received an email from John and Katrina Rudd in France on something they observed on a golf course there. They recently watched two Green Woodpeckers Picus viridis (sex not stated) "dancing" and "fighting" on the ground. The birds were "very upright with wings down" and came together "swordfencing" with their beaks. Such displays are wonderful to watch and often the birds become so involved in their battle that they ignore humans and allow close approach. Actually, this behaviour is not uncommon, indeed all European woodpeckers "fight" like this. Bodily contact, however, is not always made. When it does it is presumably because the birds are well-matched and will not back-down or retreat. Usually, head-swaying, the raising of the crown feathers, tongue flicking, spreading of the wings and body, bill thrusting and bill pointing is enough to prove superiority. Such displays of aggression occur in defensive of sites such as nest-holes, ant-hills and the like and also during the courtship period when males will try to drive off rivals and usurpers. Woodpeckers rarely fight over general territories.